Presidential campaigns are filled with potential speed bumps, some merely shaking the dust off the hubcaps, others wrecking the suspension or even knocking off the wheels. Some appear unexpectedly, others are self-constructed.

Campaign 2012 for the field of Republicans hoping to unseat Barack Obama is no exception.

Herman Cain had to pronounce himself “humble and contrite” for statements he’d made about Islam and Muslims. (He had supported a Tennessee town’s effort to ban a mosque, had said Muslims “have an objective to convert all infidels or kill them,” and had said he would think twice about naming a Muslim to his cabinet “because terrorists are trying to kill us.”)

All the GOP candidates seemed flat-footed when a debate audience booed a gay soldier who posed a question (via video from Iraq) about “don’t ask, don’t tell.”

Rick Santorum, who’d jumped right in to declare that he would reinstate the recently-repealed policy of banning openly-gay men and women from serving in the military, later told Fox News, “I condemn the people who booed that gay soldier.”

Herman Cain said he regretted not having spoken up on the soldier’s behalf "because of the controversy it has created and because of the different interpretations that it could have had.”

On the hunting camp story – the camp bore a name that included the “N” word when the Perry family acquired it in the 1980s – Cain condemned it as “just plain insensitive to a lot of black people in this country,” but then backed down a bit. Others were forced to comment as well, Santorum reluctantly suggesting that Perry might have used “poor judgment.”

While the candidates would much rather discuss their economic policies and foreign policy talking points, things like Romney’s religion keep interfering. (Jon Huntsman is a Mormon too, but he’s so far from front-runner status as to be virtually invisible.)

On Sunday’s TV talk shows, everybody was asked about the controversial statement by evangelical leader Robert Jeffress at the Values Voter Summit of social conservatives over the weekend. After introducing Perry as a “a born-again follower of Jesus Christ” while suggesting that Romney was merely “a good moral person,” the Rev. Jeffress told reporters, “Mormonism is not Christianity … Mormonism is a cult.”

Some flatly disagreed with Jeffress, others waffled.

Santorum acknowledged that Romney “says he is a Christian.”

"I believe that they believe they are Christians," Cain said of Mormons.

"None of us should sit in judgment of somebody else's religion," said former House speaker Newt Gingrich, perhaps reminding people that he used to be a Southern Baptist before converting to Roman Catholicism after his third marriage.

The issue dogged Perry, who’d taken his campaign to Iowa. In essence, he rejected the Jeffress assertion about Romney without being personally critical of a Baptist minister with a megachurch in Dallas (which might not have been appreciated by many evangelicals).

"I don't think the Mormon Church is a cult," Perry told The Des Moines Register over the weekend. "People who endorse me or people who work for me, I respect their endorsement and their work, but that doesn't necessarily mean that I endorse all of their statements."

For Romney himself, of course, it’s a major distraction. According to a Pew Research Center poll this summer, 25 percent of all voters say they would be less likely to vote for a candidate if he or she were a Mormon.

In his first race for the presidency four years ago, Romney likened himself to Kennedy in 1960 regarding separation of church and state.

In what probably was his most important political speech at the time, Romney said, “Let me assure you that no authorities of my church, or of any other church for that matter, will ever exert influence on presidential decisions.” He may have to dust off that speech and give it again.

The next Republican candidates debate is Tuesday in New Hampshire. You can expect these speed bump issues to come up there.